Metalloprotein catalysts for asymmetric synthesis Project Summary The exquisite chemo-, regio-, and stereoselectivity of enzymes make them attractive tools for organic synthesis, in particular for the generation of chiral synthons and intermediates for the synthesis of pharmaceuticals and other biologically active molecules. Reflecting this notion, there have been significant interest within the pharmaceutical industry toward integrating efficient, selective, cost-effective, and sustainable enzyme-catalyzed transformations for drug synthesis and manufacturing. Progress in this direction is critically hampered, however, by the inherently limited range of chemical transformations catalyzed by natural enzymes as compared to those accessible through chemical methods. Ramifications of our prior NIH-funded research have led to the discovery that myoglobin?a small, robust, and structurally tunable heme-containing protein?, constitutes a very promising and versatile scaffold for developing efficient and stereoselective biocatalysts for carbene transfer reactions. Building upon these exciting results, the proposed research aims at investigating and extending the scope of these hemoprotein catalysts across a broad range of carbene- mediated transformations useful for the construction of carbon?carbon, carbon?nitrogen, and carbon?sulfur bonds. A set of complementary strategies will be investigated and leveraged to enhance and modulate the catalytic activity, chemo- and stereoselectivity of these catalysts. Furthermore, valuable insights into the mechanism of these reactions and into correlations between catalyst structure and reactivity/selectivity will be gained through a combination of experimental, computational, and spectroscopic studies. These efforts will contribute to the definition of guiding principles and a general, rationally driven strategy for the design and development of myoglobin-based catalysts with high activity and fine-tuned chemo-, regio- and stereoselectivity for executing a variety of asymmetric carbene insertion reactions. These systems will provide access to chiral building blocks of immediate value for medicinal chemistry and drug discovery efforts. The synthetic utility of this new class of metalloprotein catalysts will be further demonstrated through their application for the preparation of synthetically challenging drug molecules. Ultimately, this research is expected to have a major impact toward making available new efficient, selective, and sustainable biocatalytic strategies for promoting asymmetric carbene transfer reactions, thereby overcoming outstanding challenges in this field.